Clickhouse 支持毫秒 纳秒数据 |
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在clickhouse winter/Spring 新功能介绍上说clickhouse支持了毫秒和微妙的存储和计算，来验证和测试下： DateTime64 Date and Time with subsecond resolution. DateTime64(3) — milliseconds. DateTime64(6) — microseconds. 时间范围：1970–2106. 由于暂时不知道clickhouse如何生成微妙和毫秒 使用mysql查询： mysql> select version(); +-----------+ | version() | +-----------+ | 8.0.20 | +-----------+ 1 row in set (0.00 sec) mysql> select now(6); +----------------------------+ | now(6) | +----------------------------+ | 2020-07-12 00:39:14.134716 | +----------------------------+ 1 row in set (0.00 sec)在clickhouse中创建一个表用于测试： clickhouse 的版本： Clickhouse> select * from build_options limit 6; SELECT * FROM build_options LIMIT 6 ┌─name─────────────┬─value────────────────────────────────────┐ │ VERSION_FULL │ ClickHouse 20.5.2.7 │ │ VERSION_DESCRIBE │ v20.5.2.7-stable │ │ VERSION_INTEGER │ 20005002 │ │ VERSION_GITHASH │ b9b4d9a948ceecee689a503296dba93f143dd32f │ │ VERSION_REVISION │ 54435 │ │ BUILD_DATE │ 2020-07-02 │ └──────────────────┴──────────────────────────────────────────┘ 6 rows in set. Elapsed: 0.001 sec. Clickhouse> create table t_dt(id int,createtime Datetime64(3),lastmodifytime Datetime64(6))ENGINE=MergeTree() order by id; CREATE TABLE t_dt ( `id` int, `createtime` Datetime64(3), `lastmodifytime` Datetime64(6) ) ENGINE = MergeTree() ORDER BY id Clickhouse> insert into t_dt(id,createtime,lastmodifytime)values(1,'2020-07-12 00:39:14.134','2020-07-12 00:39:14.134716'); INSERT INTO t_dt (id, createtime, lastmodifytime) VALUES Ok. 1 rows in set. Elapsed: 0.003 sec. Clickhouse> select * from t_dt; SELECT * FROM t_dt ┌─id─┬──────────────createtime─┬─────────────lastmodifytime─┐ │ 1 │ 2020-07-12 00:39:14.134 │ 2020-07-12 00:39:14.134716 │ └────┴─────────────────────────┴────────────────────────────┘ 1 rows in set. Elapsed: 0.003 sec. 可以看到已经可以支持毫秒和微妙的存储计算了。 Clickhouse> WITH toDateTime64('2020-07-12 19:20:11.123', 6) AS dt64 SELECT toStartOfSecond(dt64); WITH toDateTime64('2020-07-12 19:20:11.123', 6) AS dt64 SELECT toStartOfSecond(dt64) ┌──────toStartOfSecond(dt64)─┐ │ 2020-07-12 19:20:11.000000 │ └────────────────────────────┘ 1 rows in set. Elapsed: 0.002 sec.参考： https://github.com/ClickHouse/ClickHouse/issues/10672 |
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